In this section you will gain a deeper understanding of the Ideal Gas Law by performing some simulations.

Remember that the Ideal Gas Law is of the form:

PV = nRT = NkT

Let us investigate what happens to the volume of gas in a cylinder when other variables are changed. Thus, volume (V) will always be the dependent variable. The other variables would be the independent variables; these are: number of gas particles (n), velocity of the gas particles (v), and pressure (P) on the system. The value of these variables can be changed.

1. Use Molecular Model for an Ideal Gas Website in Workbench panel located in the lower half of this screen. Once the applet starts you will see the simulation screen as shown below. The simulation window consists of two parts: the upper part where the variables are setup and the lower part where the simulation of the cylinder-in-the-chamber is displayed.

2. There are three variables whose values you can change: particles [for specifying the number of particles], pressure [for specifying the pressure], and velocity [for specifying the velocity of the particles. ]You can reset the number of particles, pressure, and velocity in the boxes located above the cylinder. You must hit enter when you change a setting to have it take effect.

At the top left of the simulation screen you will see the volume occupied by the gas in the cylinder.

You can temporarily freeze the motion and the volume by pressing and holding any mouse button when the pointer is located anywhere within the greenshaded area.

Note: After changing the settings, be sure you allow time for the system to equilibrate after you hit "enter". Depending on the conditions, this may take between 10 and 30 seconds.

3. Read the information below the animation. Spend some time testing the simulated behavior of the gas. Change the variables and watch what happens. (NOTE: It takes at least 10 seconds for the system to adjust when you make changes in the conditions.) Make the necessary tests to answer these questions:

a. What happens to the volume when you increase the number of particles?
b. Change the velocity. How does the volume change?
c. What effect does changing the pressure have on the volume?
d. Why isn't the volume exactly constant?